In wireless communication devices such as mobile telephones, there are cases where power loss occurs due to a mismatch between the input impedance of an antenna and the output impedance of a wireless device. There has been a technique to reduce the power loss. By this technique, a variable impedance matching circuit is provided between the antenna and the wireless device, a mismatch is detected by some means, and the input impedance of the antenna and the output impedance of the wireless device are automatically matched.
However, when a detecting unit that detects a current, a voltage, and the like is provided between the antenna and the wireless device by the above described technique, there arises trade-off relations between factors such as the size, frequency range, insertion loss, orientation, and binding amount of the detecting unit. Therefore, it is difficult to reduce the size and enhance the performance of the antenna device including the variable impedance matching circuit.